If you are using a Microsoft DHCP server you must configure the additional settings for the DHCP client including default gateway and DNS servers.
Something just occurred to me, for those people that are having "Page not found" errors in IE. Since the Dash is getting it's address information from DHCP, it is presumably attempting to retrieve DNS servers from DHCP as well. Maybe your routers are not passing on DHCP info? Of course this theory is shot if your computers are working fine, but also keep in mind that DNS servers don't HAVE to be automatically populated by DHCP. So you may have manually configured them on other clients. Missing DNS server entries would cause this exact problem and could be caused by misconfigured/missing DNS information and the DHCP server.